Coal tar resins and the products produced thereby



Patented Aug.- 16,- 1938 PATENT orr lCE COAL ran aasms AND 'rnn raonnc'rs raonucnn 'rnnanar 5 John Morris Weiss. New York, N. Y., assignor to The Calorider Corporation, Greenwich,- Conn., a corporation olConneoticnt No Drawing.

8 Claims.

This invention is concerned with an improved process for the production of light colored resins from bodies of the cumarone indene type.

In the manufacture of resins from cumarone and indeneand the like, it is usual practice to take a fraction of crude coal tar naphtha containing the desired range of. polymerizable products and subject it to the polymerizing action of sulphuric acid or other polymerizing agent such as acid ferric sulphate. When sulphuric acid is used as the polymerizing agent, due to the rapid rate of polymerization, there is a very considerable evolution of heat in a short period of time, If uncontrolled, the temperature rises materially and the higher the temperature, the darker the color of the resulting resin. Since the market demand is for light colored resins, this rise of temperature is very undesirable. As a result, past processes have employed indirect water cooling and artificial refrigeration to keep the temperature of. reaction low and thereby produce a resin of light color. These efforts have been only partly successful since there is a lag in any indirect cooling effect and local superheating of the reaction mixture, before the cooling takes effect, is deleterious to the color of the finished product.

I have discovered a method of internal cooling and control which is positive, instantaneous and easily adjusted, besides having certain other advantages in special cases, which method comprises carrying on the reaction in the presence of a suitable liquid of low boiling point such as propane whereby the maximum temperature is automatically controlled by the pressure placed on the system.

To illustrate the invention. I am describing a specific embodiment thereof but I do not desire to be limited thereby but only by the claims appended to this specification.

A fraction of crude coal tar naphtha, water gas tar naphtha, gas drips naphtha, or the like, boiling substantially within the range of 150 to 200 C. and containing substantial amounts of bodies of the cumarone and indene type, is placed in a suitable closed container, provided with agitating means, and is diluted with liquid propane or other low boiling liquid whichis miscible with coal tar naphtha and is unaffected by the actionpf concentrated sulphuric acid. The amount of propane used may be varied over wide limits depending on the type of naphtha and the exact conditions under which it may be desired to operate, the amount however being always sufllcient'to maintain a substantial excess of liquid propane in mixture with 55 the naphtha during the reaction.

Application January 24, me, Serial No. 80,711

The naphtha may be precooled to'a desired temperature before introduction into the agitator, say to 25 0., and the propane added, necessarily under a pressure above atmospheric since propane boils at about C. Alternately ,if the propane and naphtha are mixed at ,a higher temperature (under the correspondingfpressure required) and an excess of propane used, thetemperature can then be reduced in the liquid inthe agitator to'any desired point above the boiling point of propane by reducing thepressure and allowing the propane to partly boil oil until the temperature is reduced to the desired point. It will be understood that propane boiling off will be recovered and again reduced to iiquid'form for reuse by compression and cooling invarious ways which are well known in the handling of liquefied gases and therefore require no specific description.

, After the mixture is reduced to the desired tem'-' perature, the addition of sulphuric acid of for example 60-66" Baum strength is started with vigorous agitation. A release valve is set on the; agitator so as to maintain a constant pressure and g as the acid is added, the heat of the reaction'is instantaneously absorbed by the boiling of! of the excess propane, thereby maintaining the reaction After the reaction under isothermal conditions. is complete, the sludge is separated and removed and the solution of polymerized product in the agitator neutralized with alkali and if necessary,

water washed to remove excess of alkali and salts. If, when operating below 0 C., water washing is used, the pressure must be raised and the contents of the agitator adjusted to a temperature above the freezing point of water. The propane left is allowed to evaporate and theresidue consisting of a resin solution in the cyclic hydrocarbons of the coal tar naphtha fraction. is transferred .to a

steam still and the'resin recovered in the usual way.

If desired, the propane may be removed either before the sludge separation or after it and the alkali treatment applied on the naphtha after propane removal. The crude naphtha may be given apreliminary treatment such as a light acid wash to remove bases and tarry constituents either before or after dissolving in propane. The propane is preferably handled in a closed cycle with suitable reliquefying means so as to keep the losses of. propane to a minimum. While propane is preferred as making possible lower temperatures, butanes, pentanes or the like may be used either alone, in mixture with each other orinmixture with propane. With the higher boiling hydrocarbons, lower temperatures may be obtained by the application of vacuum but it is undesirable to use a hydrocarbon boiling above 50 C. since the sub-- sequent separation from the unaflected coal tar naphtha then becomes more dimcult.

Paracumarone resin prepared in this way is lighter in color than a material made from the same crude with the same treatment but employing outside refrigeration. The internal control oi! my invention entirely prevents superheating and undesirable side reactions caused thereby, and hence produces a more desirable commercial light color resin product. Moreover, there are certain naphtha fractions so high in cumarone indene content that it is impractical to handle them in the usual way due to the excessive heat evolution during reaction, and the resulting strong solution of resin which is too thick to properly separate from the sludge and wash with alkali. In propane solution, such difficulties are entirely obviated. Moreover, when washing in propane solution with alkali or water, the formation of emulsions, which interfere with a clean separation, is almost entirely obviated and this feature presents a very distinct advantage over present methods of operation.

The reaction speed can be regulated to a degree by the extent of propane dilution, the more the dilution the slower the reaction speed. The combination of lower than usual temperatures, exact control of temperature without any local superheating, and the dilution of the reaction mixture makes it possible to obtain resins of practically water white color. Operating on selected crude fractions, attemperatures below 15 C. and an amount of propane selected so that at the end of the reaction there still remains in the mixture, liquid propane to the extent of at least 50% of the volume of the crude naphtha, a paracumarone type resin may be obtained which when viewed in a inch layer by transmitted light, appears substantially water white.

By a suitable arrangement of successive agitators, separators, vaporizers and condensers, the process may be made to operate continuously, mixing propane and naphtha, cooling them, contacting with acid, separating sludge, washing with alkali and water and removing residual propane, so that continuous streams of naphtha, liquid propane and acid may be fed to the cycle and propane free polymer'naphtha mixture re-.

moved, all the propane used being condensed and returned to thecycle for re-use.

I claim:

L'In the production of resinous bodies, the step which comprises mixing a naphtha containing compounds of the cumarone indene type with liquid propane to form a solution thereof, and

, adding a polymerizing agent to said mixture.

compounds of the cumarone indene type with liquid propane to form a solution thereof, adding a polymerizing agent to said mixture and maintaining a predetermined maximum temperature by controlling the pressure on the reacting system.

4. In the production of resinous bodies, the step which comprises mixing a naphtha containing compounds of the cumarone indene type with liquid propane to form a solution thereof, adding sulphuric acid oi. polymerizing strength to said mixture and maintaining a predetermined maximum temperature by controlling the pressure on the reacting system.

5. In the production of resinous bodies, the steps comprising mixing a naphtha containing compounds of the cumarone indene type with liquid propane to form a solution thereof, lowerlng the pressure to allow a part of the propane to evaporate, thereby reducing the temperature of the mixture to a point corresponding to said lower pressure and adding sulphuric acid of polymerizing strength to said cooled mixture while maintaining the pressure on the system such as to prevent the temperature rising above a predetermined point.

6. The process of producing light colored cumarone type resins, comprising contacting coal tar naphtha, diluted with propane to form a solution thereof, with sulphuric acid, removing acid sludge and excess of acid, removing propane from the naphtha resin solution, recovering propane for re-use and recovering resins from said naphtha resin solution.

'7. In the production of resinous bodies, the stepwhich comprises mixing a naphtha containing compounds of the cumarone indene type with liquid hydrocarbons from the group consisting of pentanes, butanes and propanes to form a solution thereof and adding a polymerizing agent 

